Palladium has become of increasing importance in plating because of its use as a substitute for gold in many applications, particularly applications involving electrical and electronic devices. Palladium has ideal properties for use in such applications. For example, palladium has excellent physical and chemical stability, high electrical conductivity, and high thermal conductivity. Many such applications involve electrical contact surfaces such as connector pins, relay or switch contacts, contact surfaces on printed wiring boards, etc. Much of the motivation for using palladium (or palladium alloys) lies in the lower price of palladium as compared to gold and the rapid and often unpredictability in the price of gold.
For many applications involving palladium plating, large amounts of palladium are plated very rapidly and replenishment of palladium in the bath on a more or less continuous basis becomes highly desirable. A typical example is palladium plating of contact pins for electrical connectors where large numbers of pins are electroplated at high plating speeds. Here, frequent replenishment is necessary. It is highly desirable to have a replenishment procedure which is convenient and compatible with a high speed palladium plating procedure and permits long lifetime for the palladium plating bath.